Method and device for preparing air to be supplied to a room to a desired temperature and a desired humidity

ABSTRACT

The air to be supplied to a room is brought to a desired temperature and a desired humidity through the following process steps:
         making outside air flow as a first air stream through a first line ( 20 ) and making a first portion of exhaust air coming from the room flow as a second air stream through a second line ( 21 ), wherein moisture is exchanged between the first air stream and the second air stream by means of a device for exchanging humidity,   condensing, by means of a dehumidifying and cooling device ( 19 ), moisture in the form of water from the first air stream and/or from the second air stream and/or inside the device for exchanging humidity, and   making a second portion of the exhaust air flow as a third air stream through another line ( 32 ) comprising another dehumidifying and cooling device ( 33 ) and returning said second portion back to the room, wherein in the other dehumidifying and cooling device ( 33 ) moisture is condensed from the third air stream in the form of water.

TECHNICAL FIELD

The invention relates to a method and a device for preparing air to be supplied to a room, which is designated in technical language as supply air, to a desired temperature and a desired humidity, wherein moisture and heat are exchanged with the exhaust air to be removed from the room.

BACKGROUND OF THE INVENTION

Known from U.S. Pat. No. 6,178,966 is a dehumidifying device, in which fresh outside air to be supplied to a room and exhaust air to be removed from the room are passed through two cavities separated by a water-vapor-permeable membrane in order to transfer both moisture and also heat between the two air streams. Known from EP 1521040 and EP 1748260 are devices in which the outside air and the exhaust air are passed through two separate humidity exchangers, wherein a third intermediary air stream transports moisture from one humidity exchanger to the other humidity exchanger. The third air stream makes it possible to regulate the moisture exchange. These devices are used in winter to transfer moisture and heat contained in the exhaust air to the outside air to be prepared and in summer to transfer cold contained in the exhaust air to the outside air to be prepared and moisture contained in the outside air to be prepared to the exhaust air in order to bring, with the lowest possible energy, the outside air to a desired temperature and a desired humidity, which is perceived as pleasant by persons residing in the room.

BRIEF DESCRIPTION OF THE INVENTION

It is the object of the invention to improve the preparation of the supply air.

The said object is solved according to the invention by the features of claims 1 and 6. Advantageous embodiments are obtained from the dependent claims.

The invention relates to a method for the preparation of supply air to a desired temperature and a desired humidity, wherein the supply air comprises prepared outside air and a portion of prepared exhaust air=prepared circulating air, and wherein moisture and heat are exchanged between the outside air and the exhaust air. The method comprises the steps:

-   -   making outside air flow as a first air stream through a first         line and making a first portion of exhaust air coming from the         room as a second air stream flow through a second line, wherein         moisture is exchanged between the first air stream and the         second air stream by means of a device for exchanging humidity,         e.g., by means of a single humidity exchanger or by means of         coupled humidity exchangers, e.g. by means of two humidity         exchangers coupled through a closed air circuit or liquid         circuit,     -   condensing, by means of a dehumidifying and cooling device,         moisture in the form of water from the first air stream and/or         from the second air stream and/or inside the device for         exchanging humidity, and     -   making a second portion of the exhaust air flow as a third air         stream through another line comprising another dehumidifying and         cooling device, and returning said second portion back to the         room, wherein moisture is condensed from the third air stream in         the form of water in the other dehumidifying and cooling device.

In this context, the third air stream is designated in technical terminology as circulating air.

The dehumidification and cooling of the air stream flowing through one of the necessary dehumidifying and cooling devices is preferably accomplished by means of Peltier elements.

The dehumidification and cooling of the air stream flowing through one such dehumidifying and cooling device can alternatively take place by condensing this air stream by means of a compressor, whereby the air stream is heated to a temperature above the ambient temperature so that the air stream can release heat to the surroundings, and by relaxing the condensed air stream by means of a turbine, wherein the condensed air stream is cooled to a temperature below the dew point so that moisture is separated as water.

The dehumidification and cooling of the air stream flowing through such a dehumidifying and cooling device can take place according to a further alternative, whereby the second air stream is condensed by means of a compressor and is separated into a warm and a cold air stream by means of a vortex tube, wherein the temperature of the cold air stream lies below the dew point so that moisture is separated as water.

The invention relates on the other hand to a device suitable for carrying out the method according to the invention. Such a device comprises

-   -   a first line having an inlet via which outside air can be drawn         in and an outlet via which supply air can be delivered to the         room,     -   a second line having an inlet via which exhaust air can be drawn         in and an outlet via which outgoing air can be released to the         surroundings,     -   a device for exchanging humidity between a first air stream         flowing in the first line and a second air stream flowing in the         second line,     -   a dehumidifying and cooling device, which is disposed either in         the first line or in the second line or inside said device for         exchanging humidity between the first and the second air stream,         and     -   another line having an inlet to which exhaust air can be         supplied from the room, and an outlet which opens into the room         or into the first line upstream of the outlet thereof, and     -   another dehumidifying and cooling device, which is disposed in         the other line.

The device advantageously comprises another line or other lines through which outside air can be passed to one or both dehumidifying and cooling devices and then back (as outgoing air) to the surroundings, in order to remove heat accumulating in the corresponding dehumidifying and cooling device. If necessary, these lines contain a separate fan.

The device for exchanging humidity between the first air stream flowing through the first line and the second air stream flowing through the second line is, for example, a single humidity exchanger, advantageously an air-air humidity exchanger, which has two cavities which are separated by a water-vapor-permeable membrane, wherein the two air streams can flow through the two cavities. However, it can also comprise a first and a second humidity exchanger, wherein the first humidity exchanger comprises a first cavity disposed in the first line, which is separated from a second cavity by a water-vapor-permeable membrane, wherein the second humidity exchanger comprises a third cavity disposed in the second line, which is separated from a fourth cavity by a water-vapor-permeable membrane, and wherein the second and the fourth cavity are disposed in a closed air circuit in which an air stream can circulate or in a closed liquid circuit. In this case, a dehumidifying and cooling device can be disposed in this closed air circuit or liquid circuit.

A water-vapor-permeable membrane is to be understood as any structure which is permeable for water molecules but not for air.

The invention is explained in detail hereinafter with reference to exemplary embodiments and with reference to the drawing. The figures are schematic and are not drawn to scale.

DESCRIPTION OF THE FIGURES

FIGS. 1-5 show various exemplary embodiment of a device for the preparation of outside air,

FIG. 6 shows a schematic functional diagram of a dehumidifying and cooling device, and

FIGS. 7-10 show various examples for the dehumidifying and cooling device.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 show two different exemplary embodiments of a device 1 for the preparation of outside air to a desired temperature and a desired humidity, in which the outside air exchanges moisture and heat with the exhaust air removed from the room and is supplied to the room as supply air. The device has a first inlet 2 at which the outside air is drawn in, passed as a first air stream to a first outlet 3, and there released into the room as supply air, and a second inlet 4, at which the exhaust air is drawn in, passed to a second outlet 5 as a second air stream, and there released as outgoing air. The device 1 comprises a first fan 6, a second fan 7, optionally a first filter 8, optionally a second filter 9, a heat exchanger 10, a first humidity exchanger 11 having two cavities designated as cavity 12 and cavity 13, which are separated from one another by a water-vapor-permeable membrane 14, a second humidity exchanger 15 having two cavities designated as cavity 16 and cavity 17, which are separated from one another by a water-vapor-permeable membrane 18, and a dehumidifying and cooling device 19. The outside air entering at the first inlet 2 is passed in a first line 20 as a first air stream through the first filter 8, the heat exchanger 10, and the cavity 12 of the first humidity exchanger 11 to the first outlet 3. The exhaust air entering at the second inlet 4 is passed in a second line 21 as a second air stream through the second filter 9, the cavity 16 of the second humidity exchanger 15, and the heat exchanger 10 to the second outlet 5. The device further comprises a closed air circuit 22, in which a third air stream driven by a third fan 23 circulates through the cavity 13 of the first humidity exchanger 11 and the cavity 17 of the second humidity exchanger 15. The third air stream preferably flows in counterflow to the first and to the second air stream, as shown by the arrows of the fans 6, 7, and 23 in the figures. The water-vapor-permeable membrane 14 or 18 of the two humidity exchangers 11 and 15 is permeable for water vapor but not for air. The exchange of moisture in the humidity exchangers 11 and 15 takes place in a passive manner, i.e. without supply of energy. The two filters 8 and 9 comprise a coarse particle filter 24 and an electric filter 25. The coarse particle filter 24 prevents insects or any other larger dirt particles from entering into the electric filter 25. The electric filter 25 prevents dust and other dirt from entering into the heat exchanger 10 and/or onto the membrane of the humidity exchanger. The heat exchanger 10 is preferably a plate heat exchanger. The electric filter 25 can also be integrated in the heat exchanger 10, as is described, for example, in WO 2004085946. Waste heat accumulates in the dehumidifying and cooling device 19. A third line 26 is provided for removing this waste heat to the surroundings, through which outside air is supplied to the dehumidifying and cooling device, which outside air takes up the waste heat and then releases it to the surroundings. The third line 26 opens, for example as shown, upstream of the second outlet 5 into the second line 21. In this example, a fourth fan 27 is provided in the line 26, in order to allow the cooling outside air to flow past the dehumidifying and cooling device 19. The fourth fan 27 can possibly be omitted if the first fan 6 is disposed directly downstream of the first inlet 2, as in the example according to FIG. 2.

In the first exemplary embodiment shown in FIG. 1, the dehumidifying and cooling device 19 is disposed between the cavity 17 of the second humidity exchanger 15 and the cavity 13 of the first humidity exchanger 11 in the air circuit 22.

In the second exemplary embodiment shown in FIG. 2, the dehumidifying and cooling device 19 is disposed downstream of the second filter 9 but upstream of the second cavity 16 in the second line 21 or a dehumidifying and cooling device 19′ is disposed upstream of the first outlet 3 in the first line 20 or both dehumidifying and cooling devices 19 and 19′ are disposed at the said locations.

In the exemplary embodiments shown in FIGS. 1 and 2, the heat exchanger 10 is provided to exchange heat between the exhaust air and the outside air and the two humidity exchangers 11 and 15 are provided to exchange moisture with the third air stream. Two further exemplary embodiments are shown in FIGS. 3 and 4, in which the two humidity exchangers 11 and 15 not only exchange moisture but also sufficient heat so that no separate heat exchanger is required.

The first line 20 and the second line 21 are a part of the device, as shown in the figures, on the other hand they are connected to the surroundings or the room by means of additional external lines.

The devices according to FIGS. 1 to 4 operate with two humidity exchangers, which are coupled through the closed air circuit 22 so that the exchange of moisture can be regulated. FIG. 5 shows an exemplary embodiment in which the exchange of moisture between the first air stream and the second air stream takes place by means of a single humidity exchanger 28, which comprises a cavity 29 disposed in the first line and a cavity 30 disposed in the second line, which are separated by a water-vapor-permeable membrane 31. However, the use of a single humidity exchanger of this design or another design is possible in all the exemplary embodiments.

According to the invention, in all the exemplary embodiments, as illustrated for the exemplary embodiment in FIG. 5, a first portion of the exhaust air is left to flow as a third air stream through a fourth line 32, treated, and fed back to the room again. The third air stream is designated as circulating air stream in technical terminology. The treatment of the third air stream is accomplished by means of another dehumidifying and cooling device 33, which condenses moisture in the form of water from the third air stream. The fourth line 32 has an inlet, optionally a filter 34, a fan 35, the dehumidifying and cooling device 33, and an outlet. The inlet is either directly connected to the room or, as shown, connected directly to the second line 21 downstream of its inlet 4. The outlet either opens directly into the room or, as shown, directly upstream of its outlet 3 into the first line 20. The filter 34 advantageously comprises a coarse particle filter and an electric filter.

According to the invention, such a circulating air stream is also provided in the exemplary embodiments according to FIGS. 1 to 4.

A plurality of fans are required for conveying the various air streams. The number of the fans and their arrangement inside the device 1 can vary according to the specific design. The devices 1 presented are suitable for carrying out the method according to the invention. They are to be understood as exemplary embodiments which can be modified within the scope of the technical knowledge of a person skilled in the art.

The humidity exchangers shown in FIGS. 1 to 5 are humidity exchangers, which comprise two cavities separated by a water-vapor-permeable membrane, in which humidity is exchanged through the membrane. Alternatively, humidity exchangers based on other physical principles can also be used, e.g. humidity exchangers with adsorption and desorption processes or those with absorption and degassing processes.

The devices 1 described are switchable between two operating modes, which are designated as winter operation and summer operation. These two operating modes are now explained in detail.

Winter Operation

The device 1 transfers moisture and heat contained in the exhaust air to the outside air. The first fan 6 conveys outside air into the room and the second fan 7 conveys exhaust air out from the room. The first fan 6 can be disposed anywhere in the first line 20, the second fan 7 can be disposed anywhere in the second line 21. The third fan 23 circulates the air stream in the closed air circuit 22. The dehumidifying and cooling device 19 is switched off, i.e. the air flows through the dehumidifying and cooling device 19 without releasing moisture or heat.

Summer Operation

The device 1 transfers a portion of the moisture contained in the outside air to the exhaust air and transfers a portion of the heat of the outside air to the exhaust air, i.e. the cooler exhaust air is used to cool the warmer outside air. The transfer of the moisture from the outside air to the exhaust air is accomplished by means of the two humidity exchangers 11 and 15 which are interconnected via the closed air circuit 22. Since the exhaust air cannot absorb as much moisture as is necessary, in the exemplary embodiment according to FIG. 1, the air stream circulating in the air circuit 22 is additionally dehumidified, i.e. the dehumidifying and cooling device 19 extracts from the air stream circulating in the air circuit 22 that portion of the moisture which the exhaust air cannot absorb and which must be extracted in order that the supply air has the desired humidity. In the exemplary embodiment according to FIG. 2, the exhaust air is additionally dehumidified, i.e. the dehumidifying and cooling device 19 extracts so much moisture from the exhaust air that the moisture extracted from the outside air in the humidity exchanger 11 can be transferred completely to the exhaust air by means of the humidity exchanger 15. It is also possible to dehumidify both air streams.

The first fan 6 conveys outside air into the room and the second fan 7 conveys exhaust air out from the room. The dehumidifying and cooling device 19 is operating so that the air at the outlet of the dehumidifying and cooling device 19 is drier and cooler than the air at the inlet of the dehumidifying and cooling device 19. Air circulates in the closed air circuit 22, which, depending on the design of the dehumidifying and cooling device 19, is made to flow either by the third fan 23 or by the dehumidifying and cooling device 19.

In addition, that portion of the exhaust air which flows as circulating air through the fourth line 32, is cooled and/or dehumidified by means of the dehumidifying and cooling device 33 and then returned to the room. The circulating air and the outside air are prepared so that together they supply air of the desired temperature and humidity to the room.

FIG. 6 shows a schematic functional diagram of the dehumidifying and cooling device 19, through which an air stream 38 to be treated flows. The dehumidifying and cooling device 19 has a cooling block 36 and optionally a subsequent thermal block 37. In the cooling block 36 the air stream 37 is cooled to a temperature below the dew point so that at least a portion of the moisture contained in the air condenses out as water. As described above, the heat accumulating there is supplied to the outgoing air at the second outlet 5 (FIG. 1) by means of the air stream conveyed through the line 26. If the thermal block 37 is present, a portion of the accumulating heat is supplied directly to the outgoing air and the remaining portion of the accumulating heat is supplied directly or via a line 32 to the thermal block 37 and then to the outgoing air in order to heat up again the cold air emanating from the cooling block 36.

FIGS. 7 to 10 illustrate various examples for the dehumidifying and cooling device 19, which also all contain the thermal block 37. However, the thermal block 37 can also be omitted. In this case, the accumulating heat is supplied to the outgoing air.

Example 1

In the example shown in FIG. 7, the cooling of the air stream 38 flowing through the dehumidifying and cooling device 19 in the cooling block 36 is accomplished by means of at least one Peltier element 39. Two Peltier elements 39, having a cold wall 40 and a warm wall 41 are shown in the example. The temperature of the cold wall 40 is cooled by supplying electrical energy, wherein at least the last Peltier element viewed in the direction of flow of the air stream 38 is cooled to a value which lies below the dew point of the inflowing air. The air stream 38 flowing along this cold wall 40 is cooled, wherein moisture contained in the air stream 38 condenses out in the form of water at the cold wall 40 as soon as the temperature of the air stream 38 falls below the dew point. The water is supplied via a line 42 to a collecting basin 43 or removed directly to the surroundings. The heat accumulating during cooling of the air stream 38 and during condensation of moisture as well as the electrical energy supplied to the Peltier elements 39, which is also converted into heat, reaches the warm wall 41. A portion of this heat is supplied, for example via a line 44, to the thermal block 37 and transferred in the thermal block 37 by means of a heat exchanger 45 to the air stream 38 in order to heat the air stream 38 in the thermal block 37 to a desired temperature. The remainder of the heat is released to the air flowing through the line 26. This is possible because the temperature of the warm wall 41 is higher than the temperature of the outside air.

A particularly advantageous embodiment is shown in FIG. 8. The dehumidifying and cooling device 19 comprises a plurality of Peltier elements 39 at which the air flowing past is cooled and dehumidified. The air stream 38 is then passed along the cold side of the Peltier elements 39 and then along the warm side of at least one of the Peltier elements 39. That is, the thermal block 38 is formed here by the warm side of this at least one Peltier element.

In winter operation, the dehumidifying and cooling device 19 is usually not operating since the outside air is relatively dry and does not need to be dehumidified. The Peltier elements 39 provided in this example can, however, be used to heat the air stream flowing through the dehumidifying and cooling device 19. The current flowing through the Peltier elements 39 then flows in the reverse direction so that the wall 40 is now heated and the wall 41 is cooled.

Example 2

In this example shown in FIG. 9, the cooling block 36 comprises a compressor 46, a heat release chamber 47, a turbine 48, and a condensation chamber 49, wherein the drive shafts of the compressor 46 and the turbine 48 are coupled to one another. The compressor 46 compresses the air in a mechanical manner, whereby the air is heated. When the relatively hot air flows through the heat release chamber 47, the heat release chamber 47 is heated to a temperature which lies significantly above the local ambient temperature so that the heat release chamber 47 can release heat to the surroundings. The accumulating heat is removed by the outside air flowing through the line 26. The supplied outside air therefore cools the heat release chamber 47. In this way, heat is extracted from the air stream 38. When the air stream 38 then flows through the turbine 48, it drives the turbine 48. When driving the turbine 48, the air stream 38 must perform so much mechanical work that it is cooled to a temperature below the dew point. The cold air therefore cools the condensation chamber 49 so that moisture in the condensation chamber 49 condenses in the form of water and is collected via a line 42 in a collecting basin 43 or removed directly to the surroundings. When the air stream 38 leaves the condensation chamber 49, it is cold and dry. In order to heat up the air stream 38 again, a portion of the heat accumulating in the heat release chamber 47 is supplied to the thermal block 37, for example, via two heat exchangers 45 and 52 which are interconnected by a line 44. Since the drive shafts of the compressor 46 and the turbine 48 are coupled to one another, the turbine 48 drives the compressor 46 so that merely the power P=P_(K)−P_(T) needs to be supplied to the compressor 46 from outside, where the quantity P_(K) denotes the power required by the compressor P_(K) and P_(T) denotes the power delivered by the turbine 48.

Example 3

In the example shown in FIG. 10, the dehumidifying and cooling device 19 comprises a compressor 46 and a vortex tube 53. The compressor 46 compresses the air stream 38 and thereby increases the pressure of the air so that the air stream 38 flows into the vortex tube 53 at high speed. The temperature of the air stream 38 is thereby increased. A portion of the heat is removed by means of a heat exchanger 54 via the line 26. The vortex tube 53 separates the air stream into a hot air stream and a cold air stream and is designed so that the temperature of the cold air stream lies below the dew point so that the moisture contained in the cold air stream condenses out in the form of water. The cold air stream and the hot air stream are guided in separate lines 50 or 51, so that on the one hand the water can condense out and on the other hand, heat can be extracted from the hot air stream, for example, by means of another heat exchanger 55. The dehumidified cold air stream and the hot air stream are then combined again before they leave the dehumidifying and cooling device 19. 

1. Method for the preparation of supply air to be supplied to a room to a desired temperature and a desired humidity, comprising the steps: making outside air flow as a first air stream through a first line (20) and making a first portion of exhaust air coming from the room flow as a second air stream through a second line (21), wherein moisture is exchanged between the first air stream and the second air stream by means of a device for exchanging humidity, condensing, by means of a dehumidifying and cooling device (19), moisture in the form of water from the first air stream and/or from the second air stream and/or inside the device for exchanging humidity, and making a second portion of the exhaust air flow as a third air stream through another line (32) comprising another dehumidifying and cooling device (33) and returning said second portion back to the room, wherein in the other dehumidifying and cooling device (33) moisture is condensed from the third air stream in the form of water.
 2. Method according to claim 1, characterized in that the dehumidification and cooling of the air stream flowing through the dehumidifying and cooling device (19) and/or through the other dehumidifying and cooling device (33) is accomplished by means of at least one Peltier element (39).
 3. Method according to claim 1, characterized in that the dehumidification and cooling of the air stream flowing through the dehumidifying and cooling device (19) and/or through the other dehumidifying and cooling device (33) takes place through the steps: condensing the air stream by means of a compressor (46), whereby the air stream is heated, passing an outside air stream through a heat exchanger and releasing heat of the condensed air stream to this outside air stream by means of the heat exchanger, and relaxing the condensed air stream by means of a turbine (48), whereby the condensed air stream is cooled to a temperature below the dew point so that moisture is separated as water.
 4. Method according to claim 1, characterized in that the dehumidification and cooling of the air stream flowing through the dehumidifying and cooling device (19) and/or through the other dehumidifying and cooling device (33) takes place in that this air stream is condensed by means of a compressor (46) and is separated into a warm and a cold air stream by means of a vortex tube (53), wherein the temperature of the cold air stream lies below the dew point so that moisture is separated as water.
 5. Method according to any of claims 1 to 4, characterized in that the exchange of moisture in said device for exchanging humidity takes place by means of at least one air-air humidity exchanger.
 6. Device for the preparation of supply air to be supplied to a room to a desired temperature and a desired humidity, comprising: a first line (20) having an inlet (2) via which outside air can be drawn in and an outlet (3) via which supply air can be delivered to the room, a second line (21) having an inlet (4) via which exhaust air can be drawn in from the room and an outlet (5) via which outgoing air can be released to the surroundings, a device for exchanging humidity between a first air stream flowing in the first line (20) and a second air stream flowing in the second line (21), a first dehumidifying and cooling device (19), which is disposed either in the first line (20) or in the second line (21) or inside the said device for exchanging humidity, another line (32) having an inlet to which exhaust air can be supplied from the room, and an outlet which opens into the room or into the first line (20) upstream of the outlet (3) thereof, and another dehumidifying and cooling device (33), which is disposed in the other line (32).
 7. Device according to claim 6, characterized by another line (26) through which outside air can be passed to the dehumidifying and cooling device (19) and/or to the other dehumidifying and cooling device (33) and then back to the surroundings, in order to remove heat accumulating in the corresponding dehumidifying and cooling device (19; 33).
 8. Device according to claim 6 or 7, characterized in that at least one of the dehumidifying and cooling devices contains a Peltier element (39) in order to cool the temperature of the air flowing through the dehumidifying and cooling device below the dew point.
 9. Device according to claim 6 or 7, characterized in that at least one of the dehumidifying and cooling devices contains a compressor (46) in order to condense the air and a turbine (48) in order to relax the condensed air and thereby cool the temperature of the air to a temperature below the dew point.
 10. Device according to claim 6 or 7, characterized in that at least one of the dehumidifying and cooling devices contains a compressor (46) and a vortex tube (53).
 11. Device according to any of claims 6 to 10, characterized in that the device for exchanging humidity comprises at least one air-air humidity exchanger, which has two cavities (29, 30) which are separated by a water-vapor-permeable membrane (31). 